1. Field of the Invention
The present invention relates to a particle beam therapy system, and more particularly to a particle beam therapy system in which a charged particle beam, such as a proton or carbon ion beam, is irradiated to a diseased part (tumor) for treatment.
2. Description of the Related Art
There is known a therapy method of irradiating a beam of charged particles, such as protons, to a tumor, e.g., a cancer, in a patient's body. A large-scaled one of therapy systems for use with that therapy method comprises a charged particle beam generator, a beam transport system, and a plurality of treatment rooms. A charged particle beam accelerated by the charged particle beam generator reaches an irradiation unit in each of the treatment rooms through the beam transport system, and is irradiated to the tumor in the patient's body from a nozzle of the irradiation unit. In addition, the beam transport system comprises one common beam transport system and a plurality of branched beam transport systems which are branched from the one common beam transport system and extended into the respective irradiation units in the treatment rooms. At a position where each of the branched beam transport system is branched, a switching electromagnet is disposed which deflects the charged particle beam incoming from the one common beam transport system and introduces it into the corresponding branched beam transport system (see, e.g., Patent Reference; U.S. Pat. No. 5,585,642(JP,A 11-501232); from line 47, column 4 to line 34, column 5).